Well, if you go with an non-Canon brand (Canon is NOT crappy), then make sure that your Raw conversion software has Digital Lens Optimization for the lens/camera combination. Without DLO you're not getting the most out of any lens, zooms in particular.

Dave

The latest version of Lightroom's lens database contains about every lens you could think of for a Canon (or a Sony, Nikon, Oly, etc.)

I just picked up an EF 70-300 IS USM lightly used for a steal and have been very happy with it so far. Something to consider is that any $ you invest in EF-S lens' will be wasted if you ever upgrade to a full frame body. I personally dont like to buy any ef-s lens' for my one crop sensor body because they wont work with our 3 full frame's and I like to keep everything compatible with each other.